Wax candles come in many varieties, such as tapers, pillar candles, container candles, and votive candles. Usually, such candles leave an amount of unconsumed wax at the end of the useful life thereof.
Some have attempted to minimize the amount of wax fuel left unused at the end of the candle's life. For example, one votive candle has a cup with a conically tapered bottom wall draining toward a central recess that causes melted wax to flow toward a central wick to provide complete consumption thereof. A cylindrical tube with apertures through the side wall extends upwardly from the recess and surrounds and supports the wick until the wax has been completely consumed. In another example, a wax burner in a flat-bottomed container includes a wick disposed in a hollow metal vertical tube with upper and lower radial heat fins. Holes through the tube side wall allow complete consumption of wax in the container.
In container candles, however, it was observed that sudden flare-ups, or “flash-over,” sometimes occurred when the wax level became very low. Some have tried to prevent flash-over by causing the container candle to self-extinguish before all the wax has been consumed. For example, one container candle includes an anti-flash sustainer having an upwardly extending neck that holds a wick and a flat or concave base. The lower end of the neck is sealed so that the flame will automatically extinguish after the melted wax drops below the top of the neck. The sustainer may be mounted upon an upwardly extending pedestal on the container floor to further increase the amount of unconsumed fuel in the bottom of the container. In another container candle, a conventional wick holder is located within a raised disk-shaped locating recess in the bottom wall of the container. A raised peripheral lip around the locating recess prevents wax from flowing to the wick after the wax has dropped below the level of the lip, thereby leaving unconsumed fuel in the bottom of the container surrounding the raised locating recess. Unfortunately, such designs directed at minimizing flashover events sacrifice efficient fuel consumption by leaving the unconsumed wax at the end of the candle's life.